Impression material

ABSTRACT

An impression material for the use with an impression spoon in patients, wherein the impression material comprises curable components and at least one first filler, characterized in that said at least first filler has a BET surface of from 20 to 50 m 2 /g, preferably from 30 to 40 m 2 /g, whereby the impression material attains a low thixotropy and a viscosity of from 1 to 350 Pas.

Subject matter of the present invention is an impression material foruse with an impression spoon.

WO-A-97/32536 and WO-A-98/52491 describe an impression spoon and animpression material for said impression spoon.

There, the impression material is fed from the rear ends of theimpression spoon into the mold cavity confined and sealed between theimpression spoon and the jaw and drawn through the groove of the mold tothe front end of the impression spoon under the influence of reducedpressure. An introduction of deflector elements in the form of skeletonfoams results in a flow component of the impression material parallel tothe tooth center promoting the complete impression of undercut anddeeper areas.

Using such impression spoons, one obtains highly precise impressionswhich—as compared to impressions obtained by conventional impressiontechniques—do not contain any trapped liquids (sulcus liquid, blood) orair bubbles and which do not have any defective wetting, distortions, orelastic recovery of shape after the deformation of the plasticimpression material under pressure.

The low-viscous impression materials used in the conventional impressiontechniques are not or only restrictedly usable with the new impressionspoon due to the kinetic and rheological properties thereof.

The impression materials usually used in the conventional impressiontechniques consist of a multicomponent system:

α) di- and polyalkenylsiloxanes;

β) polyhydrogensiloxanes;

γ) a precious metal catalyst of the 8th side group of the periodicsystem;

δ) reinforcing fillers;

ε) non-reinforcing fillers.

The technical problem forming the basis of the invention is theprovision of an impression compound which can be used in the novelimpression spoons according to WO-A-97/32536 and WO-A-98/52491. Anotherproblem is the provision of a formulation which does not sedimentate andseparate during storage, the rheological properties of which remainalmost unchanged and which results in a cured impression material havingmechanical properties which correspond to the features of DIN 24823 (ISO4823) as well as the required tear resistance and tear propagationresistance.

Said problem is solved by an impression material for use with animpression spoon, wherein the impression material comprises curablecomponents and at least one first filler, characterized in that said atleast one filler has a BET surface of from 20 to 50 m²/g, preferablyfrom 30 to 40 m²/g, whereby the impression material becomes slightlythixotropic and attaining a viscosity of from 1 to 350 Pas.

The impression material of the invention is advantageous in that itmeets the demands made on the use thereof in the novel impression spoon,in particular the demands made on the impression material with regard toviscosity, reaction kinetics, elastic properties and thixotropy duringthe flow of the material through the impression spoon. These are inparticular:

a) Viscosity

The impression materials of the invention used in the novel impressionspoon according to WO-A-97/32536 and WO-A-98/52491 ensure a very goodflow behavior which results in an optimal impression. Studies haverevealed that the impression results of said novel impression techniqueare the better the lower the mixed viscosity of the employed impressionmaterial is.

Preferably, low-viscous formulations having a mixed viscosity in therange of from 1 to 40 Pas are employed; especially preferred are mixedviscosities of from 1 to 10 Pas.

Low-viscous formulations in this viscosity range have been known in theart (see table 3).

The tooth impression materials having the lowest viscosity (DIN 24823,ISO 4823) obtainable on the market have a mixed viscosity of from 27 to1100 Pas. The mixed viscosities of the impression materials having thelowest viscosity (Permadyne Garant 2:1, Provil L Panasil contact plus,and Lastic Xtra superfine) exceed the ideal viscosity range of from 1 to10 Pas. Therefore, said materials used for the conventional impressiontechniques such as the correction and sandwich impressions have onlyunsatisfactory impression results in this novel impression technique.

b) Elastic Properties During the Flow Through the Impression Spoon(Reaction Kinetics)

In the novel impression technique according to WO-A-97/32536 andWO-A-98/52491 the impression spoon is filled from the rear to the front.An important criterion is that the mixed viscosity of the inventiveimpression material during the flow through the impression spoon has toremain almost constant, i.e., no or only very weak elastic properties bychemical crosslinking may be generated. Also here, the marketableproducts used for the conventional impression techniques (Aquasil LV,Xantopren XL, Coltene President light) have drawbacks. These productsare disadvantageous in that they crosslink too fast during the flowthrough the impression spoon according to WO-A-97/32536 andWO-A-98/52491 and thus generate elastic properties already during theflow through the impression spoon.

When employing the conventional impression materials as such in thenovel impression spoon, also this kinetic effect results inunsatisfactory impression results.

c) Thixotropy

The impression materials of the invention employed in the novelimpression spoon according to WO-A-97/32536 and WO-A-98/52491 ensurethat the thixotropy is as low as possible, which considerablycontributes to an optimum impression. Studies have revealed that theimpression results obtained with the use of this novel impressiontechnique are the better the lower the thixotropy of the employedimpression material is. Usually, the impression materials employed inaccordance with prior art have thixotropic properties (e.g., Panasilcontact plus, thixotropic index: 1.7).

In the novel impression technique, said impression materials revealedonly unsatisfactory impression results since said impression materialsform flow trails in the shadow area of the flow direction when flowingthrough the impression spoon from the rear to the front around theteeth.

In addition to the above-mentioned properties, the inventive impressionmaterial for the novel impression technique meets further demands whichwill be explained below:

Mechanical Properties of the Cured Impression Material

The inventive impression materials for the novel impression techniqueaccording to WO-A-97/32536 and WO-A-98/52491 meet the demands of type 3of DIN 24823 and ISO 4823, resp., with regard to the compression set inthe range of from 2 to 20% and the recovery of shape after thecompression in the range of from 96.5 to 100%, a linear dimensionalchange (polymerization shrinkage) in the range of from 0 to 1.5%, and anaccuracy of reproduction of 0.02 mm.

The Shore hardness (DIN 53505, ISO 868) of the cured impression materialof the invention is between a Shore A of from 30 to 50, preferably from35 to 45, which is advantageous for the novel impression techniqueaccording to WO-A-97/32536 and WO-A-98/52491.

Some impression materials in accordance with prior art used for theconventional impression techniques have Shore A hardnesses of >50.(Aquasil LV: Shore A of 58, Coltene, President light body: a Shore A of59). High Shore A hardnesses render the removal of the cured impressionmaterial from the mouth more difficult.

In the novel impression technique according to WO-A97/32536 andWO-A-98/52491, inventive impression materials having minimum tearresistance and tear propagation resistance values (according to DIN/EN53504 and DIN 53515) in the cured state of from 150 N/cm² to 250 N/cm²and 0.5 to 2.5 N/mm, resp., are employed.

In the novel impression technique according to WO-A97/32536 andWO-A-98/52491 the teeth are reproduced faithfully in every detail, Gapsbetween the teeth and fissures between crowns and tooth stamps arecompletely filled with impression material. After the curing of theimpression material, the tear resistance and tear propagation resistancevalues have to be so high that the impression can be removed from themouth and the impression spoon without being destroyed. On the otherside, the tear resistance and tear propagation resistance values mustnot be excessive in order to avoid excessive stresses on the patient'sattachment apparatus during the removal of the cured impression materialfrom the mouth.

The Impression Materials for the Novel Impression Technique

As mentioned above, the novel impression technique according toWO-A-97/32536 and WO-A-98/52491 makes particularly high demands on therheological properties. Surprisingly, the impression material of theinvention meets these demands.

Hereinafter, preferred embodiments of the impression material of theinvention are described.

A suitable impression material for the novel impression technique has avery low mixed viscosity (between 1 and 10 Pas) and no or only very lowthixotropic properties (thixotropic index ≦1.2, in particular ≦1.1).

A mixed viscosity between 1 and 10 Pas of the multi-component material,usually a two-component material, means that the viscosities of thesingle components are below or equal to 1 to 10 Pas and the thixotropiesare below or equal to 1.2, in particular 1.1.

Contrary to the single components of impression materials according toprior art having no or a low viscosity in the above mentioned viscosityrange of from 1 to 10 Pas, the impression materials of the invention arenot prone to a sedimentation of the fillers and a separation of thepolymers or softeners in the storage time.

The storage stability of dental impression materials in primary packagesshould be at least from 18 months to 36 months. In this time saidseparation and sedimentation phenomena may not occur since the featuresof quality of the impression material will suffer otherwise. Further,the adjusted rheological properties may only vary within narrowtolerances in the storage time in order to ensure the required flowproperties.

Above all, the poststiffening phenomenon frequently occurring in thepractice, i.e., the increase of viscosity and thixotropy in the storagetime, should be avoided as far as possible.

A certain, easily reducable thixotropy of the single components of theinventive impression material is acceptable and even advantageous forthe storage stability with regard to sedimentation and separation sincethe filler particles are kept in suspension in thixotropic singlecomponents.

The requirement for this is that the thixotropy of the single componentsaffects the thixotropy of the mixed impression mass since theflowability of the impression material in the novel impression spoonwill be impaired otherwise.

The impression material according to the invention meets the followingdemands:

The mixed viscosity is between 1 and 350 Pas, the impression materialdoes not or nearly not have thixotropic properties, the rheologicalproperties remain nearly constant in the storage time, and nosedimentation or separation occurs in the storage time.

Further, the mechanical properties of the cured impression materialconcerning the tear resistance, tear propagation resistance, Shore Ahardness, and the requirements of DIN EN 24823 (ISO 4823) meet thedemands stated above.

In a preferred embodiment, the mixed viscosity is from 1 to 40 Pas, inparticular preferably from 1 to 10 Pas. In order to realize the requiredmixed viscosities of from 1 to 350 Pa, in particular from 1 to 40 Pas,preferably from 1 to 10 Pas, the single viscosities of the singlecomponents of a two-component impression material have to be within thementioned limits. Moreover, it is also possible that one singlecomponent has a very high viscosity and the other one a very lowviscosity. According to the invention, the mixture must have a viscosityof from 1 to 350 Pas, in particular from 1 to 40 Pas, preferably from 1to 10 Pas in this case.

According to the invention, a low-viscous, non-thixotropic impressionmaterial which has a mixed viscosity within the above-mentioned limitsand a thixotropic index of from 1.0 to 1.2 and rheological propertiesremaining unchanged during the storing, which does not sedimentate inthe storage time and has mechanical properties after curing meeting thefeatures required according to ISO 4823 and the required tear resistanceand tear propagation resistance can be produced.

Preferably, this can be achieved by using a first inorganic fillerhaving a BET surface between 20 and 50 m²/g, which may be hydrophobized,in the impression material of the invention.

Especially preferred is a combination of said inorganic filler with areinforcing inorganic filler having a BET surface which is greater thanthat of the first filler and which is preferably between 50 to 700 m²/g,in particular from 110 to 170 m²/g.

Another subject matter of the present invention is a filler combinationof a first and a second filler, wherein the first inorganic filler has aBET surface of from 20 to 50 m²/g and the second filler is an inorganicreinforcing filler having a greater BET surface than the surface of thechosen first filler. Preferably, the second filler has a BET surface offrom 50 to 700 m/g, in particular from 110 to 170 m²/g.

In particular, the inorganic filler of the invention has the followingfeatures:

The density is of from 2.0 to 2.2 g/cm³, the BET surface is of from 20to 50 m²/g, in particular from 30 to 40 m²/g, e.g., about 35 m²/g. Dueto the production-engineering conditions, the BET surface has afluctuation range, the mean value of which is here Taken as a base.Typically, the fluctuation range is of from ±5 to 15 m²/g. The dibutylphthalate adsorption according to DIN 53601 is from 140 to 180 g/100 g.The oil adsorption according to DIN ISO 7875 is from 35 to 60 g/100. Themean particle size is from 0.5 to 20 μm.

Preferably, the inorganic filler of the invention is a wet-precipitatedsilicic acid or a naturally occurring silicic acid. As compared topyrogenic silicic acid, said acids may have a relatively high watercontent of from 2 to 8%.

The inorganic fillers of the invention consist of from 80 to 100% ofsilicon dioxide. Further, they may comprise other metal oxides such asaluminium oxide, calcium oxide, sodium oxide, potassium oxide, ironoxide, and titanium oxide. Especially preferred as metal oxides inaddition to silicon dioxide are calcium oxide, sodium oxide, potassiumoxide, and aluminium oxide.

In particular, the hydrophobized silicic acid which—according to theinvention—has to be employed in combination with the inventive inorganicreinforcing filler having a BET surface of from 20 to 50 m²/g has thefollowing characteristics:

The density is between 2.0 and 2.2 g/cm³, the BET surface is from 110 to170 m²/g, in particular between 130 and 150 m²/g.

The primary particle size is between 5 and 30 nm.

The hydrophobized, highly dispersed silicic acid is preferably preparedby a flame hydrolysis of silicon tetrachloride.

Said highly dispersed silicic acid is a hydrophobized, highly dispersedsilicic acid being a synthetic, X-ray amorphous silicon dioxide.

The hydrophobized, highly dispersed silicic acid is preferablysurface-treated with trimethylsilyl groups. The degree of hydrophobicityis characterized by a carbon content of from 1 to 6% and preferablybetween 2 and 3%.

In the production, said hydrophobized silicic acid is preferablysubjected to an additional refining step, an intense mechanicaltreatment by a pan mill or a ball mill.

The impression material of the invention on the basis of additioncrosslinking silicones for the impression technique employing the novelimpression spoon preferably consists of the following ingredients:

α) di- and polyalkenylsiloxanes;

β) polyhydrogensiloxanes;

γ) a precious metal catalyst of the 8th side group of the periodicsystem;

δ) optionally a reinforcing filler in the form of a hydrophobized,highly dispersed silicic acid having a BET surface of from 110 to 170m²/g;

ε) an inorganic filler having a BET surface of from 20 to 50 m²/g whichmay be hydrophobized,

and optionally auxiliary agents such as softeners, surfactants, dyes,and polyether-siloxane copolymers which optionally contain vinyl or SiHgroups.

Usually, the ingredients are divided into two separated components:

For example:

A component α)+γ)+ε)+δ)

B component β)+ε)+optionally α).

An Especially Preferred Impression Material of the Invention Has theFollowing Composition of Ingredients:

α) α,ω-vinyl-terminated polydimethylsiloxanes in a percentage range offrom 40 to 80%, in particular from 50 to 70%;

β) polyhydrogenpolydimethylsiloxanes having at least 2 SiH groups or aSiH contents of from 0.1 to 15 mmol/g in a percentage range of from 2 to40%, in particular from 10 to 30%;

γ) hydrosilylation catalysts, salts, complex and colloidal forms of thetransition metals of the 8th side group of the periodic system,preferably the platinum, palladium, and rhodium metals, in particularplatinum catalysts prepared from, e.g., hexachloroplatinic acid, or fromplatinum salts (Karstedt catalysts) in a percentage range of from 0.0001to 0.1%, in particular from 0.0005 to 0.1%, based on the pure metal;

δ) optionally a reinforcing filler in the form of hydrophobized, highlydispersed silicic acid having a BET surface of from 130 to 150 m²/g in aweight range of from 0 to 30%;

ε) an inorganic filler having a BET surface of from 30 to 40 m²/g whichmay be hydrophobized in a percentage range of from 10 to 50%, inparticular from 20 to 30%.

It has been known that the platinum catalyst is irreversibly destroyedalready in the presence of low concentrations of acids, bases, or water.This becomes apparent during a longer storage under mom temperatureconditions after about 6 months or during a temperature stress test,e.g., at 60° C., already after 1 to 2 weeks in that the crosslinkingreaction of the two-component mixture is strongly retarded or failscompletely.

This effect cannot be tolerated for a dental impression material. Acids,water, and, above all, bases initiate the cleavage of hydrogen fromhydrogenpolysiloxanes.

This results on the one hand in a swelling of the primary package due tothe development of hydrogen gas and on the other hand in a delayedcrosslinking reaction and a weakening of the cured silicone rubberduring the addition reaction of the two-component material due tomissing SiH functionalities.

Surprisingly, according to the invention also inorganic fillers having aBET surface of from 20 to 50 m²/g having a high water content of up to10% and/or a very high pH value of up to 11 may be used.

After the drying of said fillers, formulations of addition crosslinkingsilicones with said fillers are stable.

The A component of a two component impression material containing theplatinum catalyst does not exhibit any impairment of the settingkinetics in the storage time of up to 36 months. In the B componentcontaining polyhydrogensiloxanes no development of hydrogen can bedetected in this storage time.

The impression material of the invention (see examples 27, 33) isdistinguished by a very good flowability. The mixed viscosity isadjustable between 1 and 40 Pas depending on the chain length of theemployed silicone polymers; especially good impression results may beobtained with mixed viscosities between 1 and 10 Pas.

In the mixed state the impression material has no relevant thixotropicproperties. The mixed viscosity and the non-relevant thixotropicproperties remain nearly unchanged in the storage time.

The use of the inorganic filler of the invention prevents thesedimentation of the filler and the separation of the silicone polymersin the storage time of up to 36 months at room temperature.

With the impression material of the invention, the settingcharacteristics of the impression material may be adjusted within wideranges in a matter known as such, e.g., by employing and selectinginhibitors.

The processing time, i.e., the time required by the impression materialto flow through the novel impression spoon, is between 20 and 120 s,preferably between 25 and 60 s.

After the complete filling of the novel impression spoon within themouth of the patient the impression material cures within 2.0 to 10.0min. Curing times between 2.0 and 4.0 min are especially preferred sincethey reduce the expenditures in time of the attending dentist and thestress of the patient.

With respect to the impression materials in accordance with prior art,the impression material of the invention is distinguished in that themixed viscosity thereof during the flow through the impression spoonremains nearly constant, i.e., the reaction kinetics is adjusted suchthat no or only very weak elastic properties by chemical crosslinkingare created in the flow time. After termination of the flow stadium, theimpression material of the invention preferably cures very fast (snapeffect). The mechanical properties of the impression material of theinvention meet the requirements of DIN EN 24823 (ISO 4823). The recoveryof shape after deformation is between 96.5 and 100.0%, in particularbetween 99.0 and 100%. The compression set is between 2.0 and 20.0%, inparticular between 5.0 and 15.0.

The Shore A hardness of the impression material of the invention isbetween 30 and 50, in particular between 35 and 45. The tear resistanceand the tear propagation resistance of the impression material of theinvention are between 150 and 250 N/cm² and between 0.5 and 2.5 N/mm,resp. After the curing of the impression material, these mechanicalproperties of the impression material of the invention ensure anon-destructive removal of the impression spoon from the mouth of thepatient and a removal of the impression from the impression spoon. Onthe other side, the mechanical properties are designed such that anydamage of the patient's attachment apparatus during the removal from themouth is excluded.

In the following, the individual components of the impression materialsof the invention will be investigated in order to illustrate thesignificance of the blends and the optimization thereof.

Comparative Examples

a) Formulations comprised of a vinylsiloxane, a SiH siloxane, and aplatinum catalyst which do not contain any filler; in the formulationsthereof, the chain lengths of the employed silicone polymers within theindividual components may vary such that the mixed viscosity is withinthe above-mentioned limits, especially preferred from 1 to 10 Pas. Themixture of such formulations has very good flow properties. There is nothixotropy.

However, the mechanical properties of the cured impression material arecompletely insufficient independent of the degree of crosslinking (seecomparative example 3).

In all of the following examples, the maximum possible concentration ofreinforcing or non-reinforcing fillers being adjustable at the upperlimit of the mixed viscosity was added.

In all cases, silicic acids and fillers hydrophobized withtrimethylsilyl groups were employed in order to obtain a maximumcompatibility with the silicone matrix,

b) Formulations comprised of a vinylsiloxane, a SiH siloxane, a Ptcatalyst, and reinforcing fillers.

Here, the following becomes apparent:

With low and high concentrations of the highly-dispersed silicic acid(reinforcing filler) the required mixed viscosities as described undera) are attained, however, although the mechanical properties as comparedto

a) are substantially improved, they are not satisfactorily met (seecomparative examples 6 and 24).

c) Formulations comprised of a vinylsiloxane, a SiH siloxane, a Ptcatalyst, and non-reinforcing fillers.

The desired mixed viscosities are attainable even with highconcentrations of non-reinforcing fillers, however, the mechanicalproperties are not suited for an application in the novel impressiontechnique. Moreover, the employed non-reinforcing fillers sedimentate inthe storage test (see comparative examples 7, 8, 9).

d) Formulations comprised of a vinylsiloxane, a SiH siloxane, a Ptcatalyst, and a combination of a reinforcing filler and anon-reinforcing filler.

d1) In a first borderline case of possible combinations, a highconcentration of a reinforcing filler and a low concentration of anon-reinforcing filler are used.

The required mixed viscosity is adjustable, however, the mechanicalproperties of the cured impression material are also insufficient.Moreover, already in this case a tendency of a sedimentation of thenon-reinforcing fillers in the storage test occurs (see comparativeexamples 10, 11, and 12).

d2) In a second borderline case, a low concentration of a reinforcingfiller is combined with a high concentration of a non-reinforcingfiller.

The required mixed viscosity is adjustable, however, the mechanicalproperties of the cured impression material are not suitable for the usewith the novel impression technique. Moreover, a heavy, not acceptablesedimentation occurs in the storage test (see comparative examples 16,17, 18, 9, 20, and 21).

d3) With the use of medium concentrations of non-reinforcing andreinforcing fillers, the required mixed viscosity may be adjusted aswell.

In the storage time the mixed viscosity of the impression materialsincreases such that the flow properties and thus the impression resultare not ensured during storage.

The cured impression material has moderate but still insufficientmechanical properties.

In the storage test, a medium sedimentation tendency is noted (seecomparative examples 13, 14, and 15).

The above-mentioned embodiments reveal that none of the formulationsbeing within the mixed viscosity range of the impression material of theinvention, preferably between 1 and 10 Pas, meet the primaryrequirements with regard to the mechanical properties of the curedimpression material and the storage stability regarding poststiffening,separation, and sedimentation.

Hence, the positive properties resulting as such from the increase ofthe concentrations of reinforcing and non-reinforcing fillers result inrheological drawbacks; i.e., by increasing the concentration of thereinforcing fillers the viscosity of the individual component increasesdrastically. In addition, the tendency of poststiffening in the storagetime increases. With non-reinforcing fillers, a sedimentation of thefillers in the storage time and a separation of the polymers occurs. Inaddition, the tear resistance and the tear propagation resistance areimpaired.

It is especially referred to the tables following the examples whichsummarize the results of the examples.

The invention is described in more detail in the following examples:

EXAMPLE 1 Comparative Example

An A component of an impression material which does not contain anyfiller.

99 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof from 7.0 Pas at 20° C. are homogeneously mixed with 1 part of aplatinum catalyst of the Karstedt type having a pure platinum content of1% under vacuum in a vacuum mixer for 15 min.

One obtains a low-viscous paste having a viscosity of 6.4 Pas which doesnot have any thixotropy (thixotropic index: 1.0).

The rheological properties of the paste do not change, and naturally thepaste does not feature any sedimentation or separation in the storagetime.

EXAMPLE 2 Comparative Example

The B component of an impression material which does not contain anyfiller.

82 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 7.0 Pas at 20° C. are homogeneously mixed with 18 parts of apolymethylhydrogensiloxane having a viscosity of 0.2 Pas and a SiHcontents of 1.8 mmol/g, and 0.02 parts of divinyltetramethyldisiloxaneunder vacuum in a vacuum mixer for 15 min.

One obtains a low-viscous paste having a viscosity of 4.6 Pas which doesnot have any thixothropy (thixotropic index: 1.0).

The rheological properties of the paste do not change, and naturally thepaste does not feature any sedimentation or separation in the storagetime.

EXAMPLE 3 Comparative Example

A mixture of the A component of example 1 and the B component of example2.

50 parts of the A component of example 1 and 50 parts of the B componentof example 2 are ejected from a double-chamber cartridge through astatic mixer and homogeneously mixed. One obtains a low-viscous pastehaving a mixed viscosity of 5.0 Pas and no thixotropy (thixotropicindex: 1.0). The paste has a processing time at 35° C. of 60 s and iscompletely cured at 35° C. after 240 s.

After the complete curing one obtains transparent, soft, slightlyelastic and brittle, formed pieces. The recovery of shape after adeformation of the cured impression material according to ISO 4823 is99.80%. The compression set according to ISO 4823 is 11.0%. The Shore Ahardness is 18.

The tear resistance and the tear propagation resistance are notmeasurable since the test pieces cracked or fissured during the removalfrom the test piece form or the mounting in the testing apparatus.

The above-mentioned properties are insufficient for an impressionmaterial.

The material cracks or fissures during the removal from the mouth or theremoval of the impression from the impression spoon.

Such a material is unsuited for the impression technique employing thenovel impression spoon. The rheological and kinetic behavior of theimpression material and the behavior thereof in the storage test withregard to sedimentation, separation and poststiffening is good, however,the mechanical strength of the obtained vulcanizate is completelyinsufficient.

EXAMPLE 4 Comparative Example

An A component of an impression material which contains only areinforcing filler as a filler.

79 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1.0 Pas at 20° C. are homogeneously mixed with 1 part of a platinumcatalyst of the Karstedt type having a pure platinum content of 1% and21 parts of a hydrophobized (surface-treated with trimethylsilylgroups), highly dispersed silicic acid having a BET surface of 140 m²/gunder vacuum in a vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 10.0 Pas andnearly no thixotropy (thixotropic index: 1.0). The paste exhibits aslight increase of the viscosity to 11.2 mPas and a constant thixotropy(thixotropic index: 1.0) in the storage time of one week. The paste doesnot sedimentate or separate in the storage time.

EXAMPLE 5 Comparative Example

A B component of an impression material which contains only areinforcing filler as a filler.

58 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 0.2 Pas at 20° C. are homogeneously mixed with 27 parts of a branchedpolymethylhydrogensiloxane having a viscosity of 0.2 Pas and a SiHcontent of 4.3 mmol/g, 19 parts of a hydrophobized (surface-treated withtrimethylsilyl groups), highly dispersed silicic add having a BETsurface of 140 m²/g and 0.01 parts of a food dye under vacuum in avacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 9.8 Pas and a lowthixotropy (thixotropic index: 1.1). The paste exhibits a distinctincrease of the viscosity to 15.0 mPas and a thixotropic index of 1.1 inthe storage time of one week. The paste does not sedimentate or separatein the storage time.

EXAMPLE 6 Comparative Example

A mixture of the A component of example 4 and the B component of example5.

50 parts of the A component of example 4 and 50 parts of the B componentof example 5 are ejected from a double-chamber cartridge through astatic mixer and homogeneously mixed. One obtains a low-viscous pastehaving a mixed viscosity of 9.0 Pas which does not have any thixotropy(thixotropic index; 1.0). The paste has a processing time at 35° C. of30 s and is completely cured at 35° C. after 240 s.

After the complete curing, one obtains transparent, soft, elastic,formed pieces. The recovery of shape after a deformation of the curedimpression material according to ISO 4823 is 99.60%. The compression setaccording to ISO 4823 is 5.45%. The Shore: A hardness is 37. The tearresistance and the tear propagation resistance are 103 N/cm² and 0.41N/mm, resp.

The above-mentioned mechanical properties are insufficient for animpression material to be employed in the novel impression spoon. Thereis a risk that the material cracks or fissures during the removal fromthe mouth or the removal of the impression from the impression spoon.

The rheological features of the impression material after the storagetest reveal a mixed viscosity of 8.3 Pas and a thixotropic index of 1.0in the storage period (one week at 60° C.). The setting characteristicsof the impression material are nearly unchanged in the storage time,

This impression material is unsuited for the impression techniqueemploying the novel impression spoon.

Although the rheological and kinetic behavior of the impression materialand the behavior thereof in the storage test with regard tosedimentation, separation, and poststiffening are good, however, themechanical strength of the obtained vulcanizates is completelyinsufficient.

EXAMPLE 7 Comparative Example

An A component of an impression material which contains only anon-reinforcing filler.

40 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 1 part of a platinumcatalyst of the Karstedt type having a pure platinum content of 1% and59 parts of a silicon dioxide filler surface-treated with trimethylsilylgroups and having a BET surface of <1 m²/g and a mean particle size of10 μm under vacuum in a vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 8.7 Pas and a lowthixotropy (thixotropic index: 1.1). In the storage time of one week, adistinct sedimentation of the filler and a separation of the siliconepolymer occurs. Moreover, a slight increase of the viscosity to 11.8 Pasand of the thixotropy (thixotropic index: 1.1) occur in the storagetest.

EXAMPLE 8 Comparative Example

A B component of an impression material which contains not onlyreinforcing filler as the filler.

29 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20 °C. are homogeneously mixed with 6 parts of apolymethylhydrogensiloxane having a viscosity at 20° C. of 200 mPas anda SiH content of 1.8 mmol/g and 65 parts of a silicon dioxide filler(quartz) surface-treated with trimethylsilyl groups and having a BETsurface of <1 m²/g and a mean particle size of 10 μm and 0.01 parts of afood dye under vacuum in a vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 8.4 Pas and a lowthixotropy (thixotropic index: 1.2). In the storage time of one week, adistinct sedimentation of the filler and separation of the siliconepolymer occur. Moreover, nearly no increase of the viscosity of 8.6 Pasand of the thixotropy (thixotropic index: 1.2) occur in the storagetest.

EXAMPLE 9 Comparative Example

A mixture of the A component of example 7 and the B component of example8.

50 parts of the A component of example 7 and 50 parts of the B componentof example 8 are ejected from a double-chamber cartridge through astatic mixer and homogeneously mixed. One obtains a low-viscous pastehaving a mixed viscosity of 10.0 Pas and a low thixotropy (thixotropicindex: 1.1). The paste has a processing time at 35° C. of 60 s and iscompletely cured at 35° C. after 230 s.

After the complete curing, one obtains relatively hard, formed pieceshaving a low elasticity. The recovery of shape after a deformation ofthe cured impression material according to ISO 4823 is 99.4%. Thecompression set according to ISO 4823 is 1,9%. The Shore A hardness is73. The tear resistance and the tear propagation resistance are 308N/cm² and 0.77 N/mm, resp.

For a tooth impression employing the novel impression spoon the tearresistance are at the upper limit, and the Shore A hardness is excessiveso that the risk of a damage of the patient's attachment apparatusduring the removal from the mouth exists. Due to a heavy sedimentationand separation of the fillers within the A and B single components(examples 16 and 17) in the storage time, the properties required forthe mixed components are also no longer ensured. After storage, themechanical and rheological properties and the setting behavior of theimpression material may strongly be impaired by the sedimentation of thesingle components.

After the storage test of one week at 60° C., the rheological behaviorof the impression material is characterized by a mixed viscosity of 10.2Pas and a thixotropy (thixotropy index: 1.1). The settingcharacteristics of the impression material distinctly changes in thestorage time.

This example illustrates that an impression material for the novelimpression spoon is not suitable if only non-reinforcing fillers areused. In particular, the behavior concerning the sedimentation and thehigh Shore A hardness in the storage test make the use in the novelimpression technique impossible.

EXAMPLE 10 Comparative Example

An A component of an impression material containing as fillers acombination of a high concentration of reinforcing and a lowconcentration of non-reinforcing fillers.

70 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 1 part of a platinumcatalyst of the Karstedt type having a pure platinum content of 1% and24 parts of a hydrophobized (surface-treated with trimethylsilylgroups), highly dispersed silicic acid having a BET surface of 140 m²/gand 5 parts of a silicon dioxide filler (quartz) surface-treated withtrimethylsilyl groups and having a BET surface of 1 m²/g and a meanparticle size of 10 μm under vacuum in a vacuum mixer for 60 min. Oneobtains a low-viscous paste having a viscosity of 9.5 Pas and a lowthixotropy (thixotropic index: 1.0). In the storage time of one week thepaste has a low sedimentation of the filler, but no separation of thesilicone polymer occurs. Moreover, in the storage test the viscositydistinctly increases to 13.4, whereas the thixotropy remains constant(thixotropic index: 1.0).

EXAMPLE 11 Comparative Example

A B component of an impression material containing as fillers acombination of a high concentration of reinforcing and a lowconcentration of non-reinforcing fillers.

47 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 25 parts of apolymethylhydrogensiloxane having a viscosity at 20° C. of 200 mPas anda SiH content of 1.8 mmol/g and 23 parts of a hydrophobized(surface-treated with trimethylsilyl groups), highly dispersed silicicacid having a BET surface of 140 m²/g, 5 parts of a silicon dioxidefiller (quartz) surface-treated with trimethylsilyl groups and having aBET surface of <1 m²/g and a mean particle size of 10 μm, 0.02 parts ofa food dye and 0.013 parts of divinyltetramethyldisiloxane under vacuumin a vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 9.8 Pas and athixotropic index of 1.0. In the storage time a slight sedimentation ofthe fillers, but no separation of the silicone polymers occurs.Moreover, a distinct increase of the viscosity to 17.9 Pas and of thethixotropy occurs in the storage test.

EXAMPLE 12 Comparative Example

A mixture of the A component of example 10 and the B component ofexample 11.

50 parts of the A component of example 10 and 50 parts of the Bcomponent of example 12 are ejected from a doublechamber cartridgethrough a static mixer and homogeneously mixed.

One obtains a low-viscous paste having a mixed viscosity of 9.2 Pas anda low thixotropy (thixotropic index: 1.1). The paste has a processingtime at 35° C. of 60 s and is completely cured at 35° C. after 240 s.

After the complete curing, one obtains elastic, formed pieces having aShore A hardness of 31. The recovery of shape after a deformationaccording to ISO 4823 is 99.4%. The compression set according to ISO4823 is 6.4%. The tear resistance and the tear propagation resistanceare 135 N/cm² and 2.59 N/mm, resp.

For a tooth impression employing the novel impression spoon the tearresistances are insufficient. There is the risk that the material cracksor fissures during the removal from the mouth or the removal of theimpression from the impression spoon. The Shore A hardness issufficient.

The rheological behavior of the impression material after the storagetest of one week at 60° C. is characterized by an increase of the mixedviscosity to 10.7 Pas and a constant thixotropy (thixotropic index:1.0).

The setting characteristics of the impression material do not change inthe storage time.

This example illustrates that an impression material for the novelimpression spoon is not suitable if a filler combination having a lowconcentration of non-reinforcing fillers and high concentrations ofreinforcing fillers is used. The tear resistance of the cured impressionmaterial is too low and thus excludes a use in the novel impressionspoon.

EXAMPLE 13 Comparative Example

An A component of an impression material containing as fillers acombination of a medium concentration of reinforcing and a mediumconcentration of non-reinforcing fillers.

51 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 1 part of a platinumcatalyst of the Karstedt type having a pure platinum content of 1% and11 parts of a hydrophobized (surface-treated with trimethylsilylgroups), highly dispersed silicic acid having a BET surface of 140 m²/gand 37 parts of a silicon dioxide filler (quartz) surface-treated withtrimethylsilyl groups and having a BET surface of <1 m²/g and a meanparticle size of 10 μm under vacuum in a vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 9.1 Pas and athixotropic index of 1.1. In the storage time of one week the pasteexhibits a medium sedimentation of the filler and a medium separation ofthe silicone polymer. Moreover, in the storage test the viscositydistinctly increases to 18.5 Pas, whereas the thixotropy remainsconstant.

EXAMPLE 14 Comparative Example

A B component of an impression material containing as a filler acombination of a medium concentration of reinforcing and a mediumconcentration of non-reinforcing fillers.

41 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 13 parts of apolymethylhydrogensiloxane having a SiH content of 4.3 mmol/g and 10parts of a hydrophobized (surface-treated with trimethylsilyl groups),highly dispersed silicic acid having a BET surface of 140 m²g, 36 partsof a silicon dioxide filler (quartz) surface-treated with trimethylsilylgroups and having a BET surface of 1 m²/g and a mean particle size of 10μm and 0.01 parts of a food dye under vacuum in a vacuum mixer for 60min.

One obtains a low-viscous paste having a viscosity of 7.6 Pas and athixotropic index of 1.2. The paste exhibits a slight sedimentation ofthe filler and a slight separation of the silicone polymer in thestorage time of one week. Moreover, a distinct increase of the viscosityto 12.0 Pas occurs in the storage test, whereas the thixotropy remainsconstant.

EXAMPLE 15 Comparative Example

A mixture of the A component of example 13 and the B component ofexample 14.

50 parts of the A component of example 13 and 50 parts of the Bcomponent of example 14 are ejected from a double-chamber cartridgethrough a static mixer and homogeneously mixed.

One obtains a low-viscous paste having a mixed viscosity of 9.5 Pas anda thixotropic index of 1.0. The paste has a processing time at 35° C. of40 s and is completely cured at 35° C. after 240 s.

After the complete curing, one obtains relatively hard, slightlyelastic, formed pieces. The recovery of shape after a deformationaccording to ISO 4823 is 99.4%. The compression set according to ISO4823 is 3.3%. The Shore A hardness is 54. The tear resistance and thetear propagation resistance are 203 N/cm² and 0,64 N/mm, resp. The tearresistance are well suited for a tooth impression employing the novelimpression spoon, the Shore A hardness, however, is slightly excessive.

The rheological behavior of the impression material after the storagetest of one week at 60° C. is characterized by an increase of the mixedviscosity to 13.9 Pas and of the thixotropy (thixotropic index: 1.4).The setting characteristics of the impression material do not change inthe storage time. Due to the heavy sedimentation and separation of thefillers within the single components A and B (examples 13 and 14) in thestorage time, also the required properties of the mixed components areno longer ensured.

After storage, the mechanical and rheological properties and the settingbehavior of the impression material may severely be impaired due to thesedimentation of the single components.

This example illustrates that an impression material containing a fillercombination with a medium concentration of reinforcing andnon-reinforcing fillers is not suited for the novel impression spoonsince the formulation has a distinct sedimentation of fillers and thus astorage stability is not attained. Due to the distinct thixotropy andthe viscosity and thixotropy increases after storage, the flow behavioris not suited for a use in the novel impression spoon.

EXAMPLE 16 Comparative Example

An A component of an impression material containing as fillers acombination of a low concentration of reinforcing fillers and a highconcentration of non-reinforcing fillers.

47 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 1 part of a platinumcatalyst of the Karstedt type having a pure platinum content of 1% and 4parts of a hydrophobized, highly dispersed silicic acid having a BETsurface of 140 m²/g and 48 parts of a silicon dioxide filler (quartz)surface-treated with trimethylsilyl groups and having a BET surface of<1 m²/g and a mean particle size of 10 μm under vacuum in a vacuum mixerfor 60 min.

One obtains a low-viscous paste having a viscosity of 9.0 Pas and athixotropic index of 1.0. In the storage time of one week the pasteexhibits a heavy sedimentation of the fillers and a heavy separation ofthe silicone polymer. Moreover, in the storage test an increase of theviscosity to 11.0 Pas and of the thixotropy (thixotropic index: 1.1)occurs.

EXAMPLE 17 Comparative Example

A B component of an impression material containing as fillers acombination of a low concentration of reinforcing fillers and a highconcentration of non-reinforcing fillers.

26 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 16 parts of apolymethylhydrogensiloxane having a viscosity at 20° C. of 200 mPas anda SiH content of 1.8 mmol/g and 4 parts of a hydrophobized(surface-treated with trimethylsilyl groups), highly dispersed silicicacid having a BET surface of 140 m²/g, 54 parts of a silicon dioxidefiller (quartz) surface-treated with trimethylsilyl groups and having aBET surface of 1 m²/g and a mean particle size of 10 μm, 0.02 parts of afood dye and 0.02 parts of divinyltetramethyldisiloxane under vacuum ina vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 9.9 Pas and athixotropic index of 1.3. The paste exhibits a heavy sedimentation ofthe filler and a heavy separation of the silicone polymers in thestorage time. Moreover, a distinct increase of the viscosity to 15 Pasand of the thixotropy (thixotropic index: 1.5) occurs in the storagetest.

EXAMPLE 18 Comparative Example

A mixture of the A component of example 16 and the B component ofexample 17.

50 parts of the A component of example 16 and 50 parts of the Bcomponent of example 17 are ejected from a double-chamber cartridgethrough a static mixer and homogeneously mixed.

One obtains a low-viscous paste having a mixed viscosity of 8.5 Pas anda thixotropic index of 1.1 The paste has a processing time at 35° C. of60 s and is completely cured at 35° C. after 240 s. After the completecuring one obtains elastic, formed pieces having a Shore A hardness of57.

The recovery of shape after a deformation according to ISO 4823 is99.70%. The compression set according to ISO 4823 is 2.7%. The tearresistance and the tear propagation resistance are 272 N/cm² and 0,73N/mm, resp. The tear resistance and the Shore A hardness are well suitedfor a tooth impression employing the novel impression spoon.

The rheological behavior of the impression material after the storagetest of one week at 60° C. is characterized by an increase of the mixedviscosity to 12.4 Pas and a constant thixotropy (thixotropic index:1.1). In the storage time, the setting time of the impression materialdecreases to 185 s.

Due to the strong sedimentation and separation of the fillers within thesingle components A and B (examples 16 and 17) in the storage time, alsothe required properties of the mixed components are no longer ensured.

After storage, the mechanical and rheological properties and the settingbehavior of the impression material will severely be impaired due to thesedimentation of the single components.

This example illustrates that an impression material containing a fillercombination with low concentrations of reinforcing fillers and highconcentrations of non-reinforcing fillers is not suited for the novelimpression spoon.

EXAMPLE 19 Comparative Example

An A component of an impression material containing as filers acombination of a low concentration of reinforcing fillers (BET surface;200 m²/g) and a high concentration of non-reinforcing fillers.

54 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 1 part of a platinumcatalyst of the Karstedt type having a pure platinum content of 1% and 4parts of a hydrophobized (surface-treated with trimethylsilyl groups),highly dispersed silicic acid having a BET surface of 200 m²/g and 41parts of a silicon dioxide filler (quartz) surface-treated withtrimethylsilyl groups and having a BET surface of <1 m²/g and a meanparticle size of 10 μm under vacuum in a vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 8.5 Pas and athixotropic index of 1.1. In the storage of one week at 60° C. the pasteexhibits a heavy sedimentation of the fillers and a heavy separation ofthe silicone polymer, Moreover, in the storage test a distinct increaseof the viscosity to 8.8 Pas occurs, whereas the thixotropy remainsconstant.

EXAMPLE 20 Comparative Example

A B component of an impression material containing as fillers acombination of a low concentration of reinforcing fillers (BET surface:200 m²/g) and a high concentration of non-reinforcing fillers.

34 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 20 parts of apolymethylhydrogensiloxane having a viscosity at 20° C. of 200 mPas anda SiH content of 1.8 mmol/g and 4 parts of a hydrophobized(surface-treated with trimethylsilyl groups), highly dispersed silicicacid having a BET surface of 200 m²/g, 42 parts of a silicon dioxidefiller (quartz) surface-treated with trimethylsilyl groups and having aBET surface of <1 m²/g and a mean particle size of 10 μm, 0.02 parts ofa food dye and 0.02 parts of divinyltetramethyldisiloxane under vacuumin a vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 9.4 Pas and athixotropic index of 1.2. The paste exhibits a heavy sedimentation ofthe fillers and a heavy separation of the silicone polymers in thestorage time. Moreover, a distinct increase of the viscosity to 13.4 Pasand of the thixotropy (thixotropic index: 1.7) occurs in the storagetest.

EXAMPLE 21 Comparative Example

A mixture of the A component of example 19 and the B component ofexample 20.

50 parts of the A component of example 19 and 50 parts of the Bcomponent of example 20 are ejected from a double-chamber cartridgethrough a static mixer and homogeneously mixed.

One obtains a low-viscous paste having a mixed viscosity of 6.4 Pas anda thixotropic index of 1.1. The paste has a processing time at 35° C. of60 s and is completely cured at 35° C. after 230 s. After the completecuring one obtains elastic, formed pieces having a Shore A hardness of51.

The recovery of shape after a deformation according to ISO 4823 is99.60%. The compression set according to ISO 4823 is 3.4%. The tearresistance and the tear propagation resistance are 170 N/cm² and 0,59N/mm, resp. Directly after the preparation of the tooth impressionmaterial, the tear resistance and the Shore A hardness are well suitedfor an impression employing the novel impression spoon material.

The rheological behavior of the impression material after the storagetest of one week at 60° C. is characterized by an increase of the mixedviscosity to 7.6 Pas and of the thixotropy. In the storage time, thesetting time of the impression material decreases to 175 s.

Due to the strong sedimentation and separation of the fillers within thesingle components A and B (examples 19 and 20) in the storage time, alsothe required properties of the mixed components are no longer ensured.

After storage, the mechanical and rheological properties and the settingbehavior of the impression material will severely be impaired due to thesedimentation of the single components.

This example illustrates that an impression material containing a fillercombination with low concentrations of reinforcing fillers (BET surface:200 m²/g) and high concentrations of non-reinforcing fillers is notsuited for the novel impression spoon.

EXAMPLE 22 Comparative Example

An A component of an impression material containing as a filler only areinforcing filler (BET surface: 200 m²/g).

91 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1.0 Pas at 20° C. are homogeneously mixed with 1 part of a platinumcatalyst of the Karstedt type having a pure platinum content of 1% and 8parts of a hydrophobized (surface-treated with trimethylsilyl groups),highly dispersed silicic acid having a BET surface of 200 m²/g undervacuum in a vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 9.2 Pas and athixotropic index of 1.0. In the storage time of one week, the pasteexhibits nearly no change of the viscosity and the thixotropy.

Naturally, the paste has no sedimentation or separation in the storagetime.

EXAMPLE 23 Comparative Example

A B component of an impression material containing only a reinforcingfiller (BET surface; 200 m²/g) as a filler.

58 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1.0 Pas at 20° C. are homogeneously mixed with 32 parts of apolymethylhydrogensiloxane having a viscosity at 20° C. of 0.2 Pas and aSiH content of 1.8 mmol/g and 10 parts of a hydrophobized(surface-treated with trimethylsilyl groups), highly dispersed silicicacid having a BET surface of 200 m²/g and 0.01 parts of a food dye undervacuum in a vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 9.1 Pas and athixotropic index of 1.0. The paste exhibits nearly no viscosity andthixotropy changes after the storage time of one week.

In the storage test no sedimentation or separation of the paste occurs.

EXAMPLE 24 Comparative Example

A mixture of the A component of example 22 and the B component ofexample 23.

50 parts of the A component of example 22 and 50 parts of the Bcomponent of example 23 are ejected from a double chamber cartridgethrough a static mixer and homogeneously mixed.

One obtains a low-viscous paste having a mixed viscosity of 7.1 Pas anda thixotropic index of 1.1. The paste has a processing time at 35° C. of60 s and is completely cured at 35° C. after 240 s.

After the complete curing, one obtains transparent, soft, elastic,formed pieces. The recovery of shape after a deformation according toISO 4823 is 99.70%. The compression set according to ISO 4823 is 6.4%.The Shore A hardness is 31. The tear resistance and the tear propagationresistance are 40 N/cm² and 0,32 N/mm, resp.

For a tooth impression employing the novel impression spoon themechanical properties are insufficient. There is the risk that thematerial cracks or fissures during the removal from the mouth or theremoval of the impression from the impression spoon.

The rheological behavior of the impression material after the storagetest is characterized by a mixed viscosity to 7.4 Pas and a thixotropicindex of 1.0 after storage (1 week at 60° C.). In the storage time, thesetting characteristics of the impression material changes to an settingtime of 280 s.

EXAMPLE 25 According to the Invention

An A component of an impression material of the invention for the novelimpression spoon having a mixed viscosity of about 7.5 Pas.

72 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 1 part of a platinumcatalyst of the Karstedt type having a pure platinum content of 1% and25 parts of a hydrophilic, wet-precipitated silicic acid having calciumoxide content of 6% and a BET surface of 35 m²/g, which was brought to aresidual water content of 0.3% by a 48 h drying at 130° C., and 2 partsof a hydrophobized (surface-treated with trimethylsilyl groups), highlydispersed silicic acid having a BET surface of 140 m²/g under vacuum ina vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 6.7 Pas and athixotropic index of 1.1. In the storage time of three weeks at 60° C.,the paste exhibits no sedimentation of the fillers and no separation ofthe silicone polymers.

In the storage test, the viscosity increases to 8.1 Pas and thethixotropy increases (thixotropic index: 1.4).

EXAMPLE 26 According to the Invention

A B component of an impression material of the invention for the novelimpression spoon having a mixed viscosity of about 7.5 Pas.

47 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 26 parts of apolymethylhydrogensiloxane hydrogensiloxane having a viscosity at 20° C.of 200 mPas and a SiH content of 1.80 mmol/g, 25 parts of a hydrophilic,wet-precipitated silicic acid having a calcium oxide content of 6% and aBET surface of 35 m²/g, which was brought to a residual water content of0.3% by a 48 h drying at 130° C., and 2 parts of a hydrophobized(surface-treated with trimethylsilyl groups), highly dispersed silicicacid having a BET surface of 140 m²/g under vacuum in a vacuum mixer for60 min.

One obtains a low-viscous paste having a viscosity of 7.3 Pas and athixotropic index of 1.0. In the storage time of three weeks at 60° C.,the paste exhibits no sedimentation of the fillers and no separation ofthe silicone polymers.

In the storage test, the viscosity increases to 7.9 Pas: and thethixotropy slightly increases (thixotropic index: 1.1).

EXAMPLE 27 According to the Invention

A mixture of the A component of example 25 and the B component ofexample 26.

50 parts of the A component of example 25 and 50 parts of the Bcomponent of example 26 are ejected from a double-chamber cartridgethrough a static mixer and homogeneously mixed.

One obtains a low-viscous paste having a mixed viscosity of 7.3 Pas anda thixotropic index of 1.1. The paste has a processing time at 35° C. of60 s and is completely cured at 35° C. after 215 s.

After the complete curing, one obtains elastic, formed pieces having aShore A hardness of 41. The recovery of shape after a deformationaccording to ISO 4823 is 99.90%. The compression set according to ISO4823 is 6.40%. The tear resistance and the tear propagation resistanceare 225 N/cm² and 0,59 N/mm, resp.

The mechanical properties are very well suited for a tooth impressionemploying the novel impression spoon. The removal from the mouth cangently be performed without any risk for the Patient's attachmentapparatus. Due to the high tear resistance thereof, the cured materialdoes not exhibit any unwanted fissuring during the removal from themouth or the removal of the impression from the impression spoon, Therheological behavior of the inventive impression material after thestorage test is characterized by a constant thixotropy (thixotropicindex: 1.1). Also the setting behavior of the impression material doesnot change in the storage time.

Thus, it is ensured that the very good flow behavior and with that theprecision of the impression results will be maintained also in thestorage time of the impression material of the invention.

When using the impression material of the invention in the novelimpression spoon in the patient's mouth, one obtains excellent, highlyprecise impression results.

This example illustrates that an impression material for the novelimpression spoon is very well suited with regard to the rheologicalproperties, the mechanical properties, the kinetic behavior and thebehavior in the storage test when employing the filler to be usedaccording to the invention having a BET surface of from 20 to 50 m²/g.

EXAMPLE 28 According to the Invention

An A component of an impression material for the novel impression spoon,wherein the filler of the invention was employed undried.

72 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 1 part of a platinumcatalyst of the Karstedt type having a pure platinum content of 1% and25 parts of a hydrophilic, wet-precipitated silicic add having calciumoxide content of 6% and a BET surface of 35 m²/g, which is employedundried and has a water content of 6,0%, 2 parts of a hydrophobized(surface-treated with trimethylsilyl groups), highly dispersed silicicacid having a BET surface of 140 m²/g under vacuum in a vacuum mixer for60 min.

One obtains a low-viscous paste having a viscosity of 6.7 Pas and athixotropic index of 1.1. In the storage time of one week at 60° C., thepaste exhibits no sedimentation of the fillers and no separation of thesilicone polymers.

In the storage test, the viscosity increases to 8.1 Pas and thethixotropy increases (thixotropic index: 1.4).

Already after a storage time at 60° C. of one week, the paste has abrown discoloration due to a decomposition of the platinum catalyst.This is due to the presence of water in the undried filler.

EXAMPLE 29 According to the Invention

A B component of an impression material of the invention for the novelimpression spoon.

47 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 1000 mPas at 20° C. are homogeneously mixed with 26 parts of apolymethylhydrogensiloxane hydrogensiloxane having a viscosity at 20° C.of 200 mPas and a SiH content of 1.80 mmol/g, 25 parts of a hydrophilic,wet-precipitated silicic acid having a calcium oxide content of 6%, aBET surface of 35 m²/g, and a water content of 6% which was brought to aresidual water content of 0.3% by a 48 h drying at 130° C., and 2 partsof a hydrophobized (surface-treated with trimethylsilyl groups), highlydispersed silicic acid having a BET surface of 140 m²/g under vacuum ina vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 7.3 Pas and athixotropic index of 1.0. In the storage time of three weeks at 60° C.,the paste exhibits no sedimentation of the fillers and no separation ofthe silicone polymers. In the storage test, the viscosity increases to7.9 Pas and the thixotropy slightly increases (thixotropic index: 1.1).

Already after a storage of one week at 60° C., the aluminium tubes usedas storage packages are distinctly swollen. This is due to the hydrogendeveloped during the reaction of the SiH crosslinking agent with thewater contained in the filler.

EXAMPLE 30 According to the Invention

A mixture of the A component of example 28 and the B component ofexample 29.

50 parts of the A component of example 28 and 50 parts of the Bcomponent of example 29 are ejected from a double-chamber cartridgethrough a static mixer and homogeneously mixed.

One obtains a low-viscous paste having a mixed viscosity of 7.3 Pas anda thixotropic index of 1.1.

Immediately after the preparation, the paste has the same positiveproperties as the impression material of example 27.

However, after a one week storage at 60° C. the impression materialsuffers from a severe increase of the setting time as compared with theinitial value of 215 s (end of setting: 600 s) due to the instabilitiesof the single components caused by the high water content of the fillerdescribed in examples 28 and 29.

Therefore, a use of the filler to be used according to the invention inan undried form for an impression material to be employed in the newimpression spoon is not optimal.

EXAMPLE 31 According to the Invention

An A component of an inventive impression material for the novelimpression spoon having a mixed viscosity of about 40 Pas.

72 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 7,0 Pas at 20° C. are homogeneously mixed with 1 part of a platinumcatalyst of the Karstedt type having a pure platinum content of 1% and25 parts of a hydrophilic, wet-precipitated silicic acid having calciumoxide content of 6% and a BET surface of 35 m²/g, which was brought to aresidual water content of 0.3% by a 48 h drying at 130° C., and 2 partsof a hydrophobized (surface-treated with trimethylsilyl groups), highlydispersed silicic acid having a BET surface of 140 m²/g under vacuum ina vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 36,8 Pas and athixotropic index of 1.2. In the storage time of three weeks at 60° C.,the paste exhibits no sedimentation of the fillers and no separation ofthe silicone polymers.

In the storage test, the viscosity increases to 38,2 Pas and thethixotropy remains nearly constant (thixotropic index: 1.2).

EXAMPLE 32 According to the Invention

A B component of an impression material of the invention for the novelimpression spoon having a mixed viscosity of about 40 Pas.

60 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 7.0 Pas at 20° C. are homogeneously mixed with 13 parts of apolymethylhydrogensiloxane having a SiH content of 1.8 mmol/g, 25 partsof a hydrophilic, wet-precipitated silicic acid having a calcium oxidecontent of 6% and a BET surface of 35 m²/g, which was brought to aresidual water content of 0.3% by a 48 h drying at 130° C., and 2 partsof a hydrophobized (surface-treated with trimethylsilyl groups), highlydispersed silicic acid having a BET surface of 140 m²/g under vacuum ina vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 25.5 Pas and athixotropic index of 1.1. In the storage time of three weeks at 60° C.,the paste exhibits no sedimentation of the fillers and no separation ofthe silicone polymers.

In the storage test, the viscosity increases to 28.4 Pas and thethixotropy slightly increases (thixotropic index: 1.2).

EXAMPLE 33 According to the Invention

A mixture of the A component of example 31 and the B component ofexample 32 having a mixed viscosity of about 40 Pas.

50 parts of the A component of example 31 and 50 parts of the Bcomponent of example 32 are ejected from a double-chamber cartridgethrough a static mixer and homogeneously mixed.

One obtains a low-viscous paste having a mixed viscosity of 39.8 Pas anda thixotropic index of 1.1.

The paste has a processing time at 35° C. of 60 s and is completelycured at 35° C. after 180 s.

After the complete curing, one obtains elastic, formed pieces having aShore A hardness of 35. The recovery of shape after a deformationaccording to ISO 4823 is 4,60%. The tear resistance and the tearpropagation resistance are 174 N/cm² and 2.09 N/mm, resp,

The mechanical properties are very well suited for an impressionemploying the novel impression spoon. The removal from the mouth cangently be performed without any risk for the Patient's attachmentapparatus. Due to the high tear resistance thereof, the cured materialdoes not exhibit any unwanted fissuring during the removal from themouth or the removal of the impression from the impression spoon. Therheological behavior of the inventive impression material after thestorage test is characterized by a nearly unchanged mixed viscosity of39.9 Pas and a constant thixotropy (thixotropic index: 1.1). Also thesetting behavior of the impression material does not change in thestorage time.

Thus, it is ensured that the very good flow behavior and with that theprecision of the impression will be maintained also in the storage timeof the impression material of the invention.

When using the impression material of the invention in the novelimpression spoon in the patient's mouth, one obtains excellent, highlyprecise impression results.

This example illustrates that an impression material for the novelimpression spoon having a mixed viscosity of 40 Pas is very well suitedwith regard to the rheological properties, the kinetic behavior and thebehavior in the storage test when employing the filler to be usedaccording to the invention having a BET surface of from 20 to 50 m²/g.In comparison with example 27, one obtains not very good, but only goodimpression results due to the higher mixed viscosity of 40 Pas. Thislower quality becomes apparent in difficult preparation situationsexisting behind voluminous teeth at the side averted from the flowdirection. Here, the flowing around these difficultly accessible areasmay be incomplete. This manifests itself in defects in the finishedimpression. This effect does not occur in example 27 according to theinvention having the especially preferred viscosity range of from 1 to10 Pas,

EXAMPLE 34 Comparative Example

An A component of a commercial, low-viscous tooth impression materialused for conventional impression techniques (material for correctionimpressions).

The A component exists as a low-viscous paste having a viscosity of 10.9Pas and a high thixotropy (thixotropic index: 9.0).

During a one week storage at 60° C., the viscosity of the pastedistinctly increases to 23.0 Pas, whereas the thixotropy is still high(thixotropic index: 5.7).

In the storage time, the paste exhibits no sedimentation of the fillersand no separation of the silicone polymers.

EXAMPLE 35 Comparative Example

The B component of a commercial, low-viscous tooth impression material(material for correction impressions) used in conventional impressiontechniques.

The B component exists as a low-viscous paste having a viscosity of 16Pas and a high thixotropy (thixotropic index: 49.0).

In a one week storage at 60° C., the paste exhibits an increase of theviscosity to 20.0 Pas and of the thixotropy (thixotropic index: 63.8).

In the storage time, the paste exhibits no sedimentation of the fillersand no separation of the silicone polymers.

EXAMPLE 36 Comparative Example

A mixture of the A component of example 34 and the B component ofexample 35 (commercial impression materials for conventional impressiontechniques).

50 parts of the A component of example 34 and 50 parts of the Bcomponent of example 35 are ejected from a double-chamber cartridgethrough a static mixer and homogeneously mixed.

One obtains a low-viscous paste having a mixed viscosity of 38.9 Pas anda thixotropic index of 1.7.

The paste has a processing time at 35° C. of 60 s and is completelycured at 35° C. after 150 s. After the complete curing, one obtainselastic, formed pieces having a Shore A hardness of 46. The recovery ofshape after a deformation according to ISO 4823 is 99.80%. Thecompression set according to ISO 4823 is 4,60%. The tear resistance andthe tear propagation resistance are 200 N/cm² and 2.09 N/mm, resp. Themechanical properties would be well suited for a tooth impressionemploying the novel impression spoon. However, when used in the novelimpression spoon in the patient's mouth, the strongly thixotropic flowproperties of the commercial impression material result in flow trailswhen the material flows around the teeth in the areas averted from theflow direction, and these flow trails severely falsify the impressionresult. A use in the novel impression spoon is not advantegeous.

EXAMPLE 37 According to the Invention

The B component of an impression material of the invention for the novelimpression spoon having a mixed viscosity of about 7.5 Pas.

46 parts of a vinyl-terminated polydimethylsiloxane having a viscosityof 7000 mPas at 20° C. are homogeneously mixed with 20 parts of apolymethylhydrogensiloxane having a viscosity at 20° C. of 200. mPas anda SiH content of 1.8 mmol/g, 7 parts of a polysiloxane-polyethercopolymer having a viscosity of 200 mPas and vinyl content of 0.15mmol/g, 25 parts of a hydrophilic, wet-precipitated silicic acid havinga calcium oxide content of 6% and a BET surface of 35 m²/g, which wasbrought to a residual water content of 0.3% by a 48 h drying at 130° C.,and 2 parts of a hydrophobized (surface-treated with trimethylsilylgroups), highly dispersed silicic acid having a BET surface of 140 m²/gunder vacuum in a vacuum mixer for 60 min.

One obtains a low-viscous paste having a viscosity of 7.3 Pas and athixotropic index of 1.0. In the storage time of three weeks at 60° C.,the paste exhibits no sedimentation of the fillers and no separation ofthe silicone polymers. In the storage test, the viscosity increases to7.9 Pas and the thixotropy slightly increases (thixotropic index: 1.1).

EXAMPLE 38 According to the Invention

A mixture of the A component of example 25 and the B component ofexample 37.

50 parts of the A component of example 25 and 50 parts of the Bcomponent of example 37 are ejected from a double-chamber cartridgethrough a static mixer and homogeneously mixed.

One obtains a low-viscous paste having a mixed viscosity of 7.3 Pas anda thixotropic index of 1.1. The paste has a processing time at 35° C. of60 s and is completely cured at 35° C. after 215 s.

After the complete curing, one obtains elastic, formed pieces having aShore A hardness of 41. The recovery of shape after a deformationaccording to ISO 4823 is 99.90%. The compression set according to ISO4823 is 6.40%. The tear resistance and the tear propagation resistanceare 225 N/cm² and 0.59 N/mm, resp.

The mechanical properties are well suited for a tooth impressionemploying the novel impression spoon. The removal from the mouth cangently be performed without any risk for the Patient's attachmentapparatus. Due to the high tear resistance thereof, the cured materialdoes not exhibit any unwanted fissuring during the removal from themouth or the removal of the impression from the impression spoon. Therheological behavior of the inventive impression material after thestorage test is characterized by a unchanged thixotropy (thixotropicindex: 1.1). Also the setting behavior of the impression material doesnot change in the storage time.

Thus, it is ensured that the very good flow behavior and with that theprecision of the impression will be maintained also in the storage timeof the impression material of the invention.

When using the impression material of the invention in the novelimpression spoon in the patient's mouth, one obtains excellent, highlyprecise impression results.

This example illustrates that an impression material for the novelimpression spoon is very well suited with regard to the rheologicalproperties, the mechanical properties, the kinetic behavior and thebehavior in the storage test when employing the filler to be usedaccording to the invention having a BET surface of from 20 to 50 m²/g.

In addition, this example illustrates that the inventive filler exertsits outstanding properties with regard to the sedimentation andseparation behaviors and the thixotropy of the mixture with the use of asilicone polyether. Moreover, the filler of the invention suppresses thenatural demixing tendency of a silicone polyether in a siliconecopolymer matrix. Due to the hydrophilic properties of the siliconepolyether, the use thereof in turn results in excellent impressionresults during the curing within the patient's mouth. The siliconepolyether is incorporated in the network during the curing of thetwo-component material of the invention and therefore not washed outduring the disinfection of the finished impression. This, in turn,results in a good flowing of the plaster around the impression duringthe subsequent casting with aqueous thin plaster and with that in anexcellent quality of the model.

TABLE 1 technical data of the examples (single components) Examples 1 to23, 28, 29, 34, and 35 are comparative examples Examples 25, 26, 31, and32 are examples according to the invention Storage tests RT/60° C.Viscosity Thixotropic Viscosity¹⁾ Thixotropic Sedimentation Separation 1week at 60° C. index 1 week Description [Pas] index²⁾ only at RT only atRT [Pas] at 60° C. Ex. 1 Without fillers, component A 6.4 1.0 None None6.4 1.0 Ex. 2 Without fillers, component B 4.6 1.0 None None 4.6 1.0 Ex.4 Only reinforcing fillers, BET: 140 m²/g, A 10.0 1.0 None None 11.2 1.0component Ex. 5 Only reinforcing fillers, BET: 140 m²/g, B 9.8 1.1 NoneNone 15.0 1.1 component Ex. 7 Only non-reinf. fillers, BET: 140 m²/g, A8.7 1.1 Severe Severe 11.8 1.1 component Ex. 8 Only non-reinf. fillers,BET: 140 m²/g, B 8.4 1.2 Severe severe 8.6 1.2 component Ex. 10 Highconc. of reinf. fillers, low conc. of non-reinf. 9.5 1.0 None None 13.41.0 fillers, A component Ex. 11 High conc. of reinf. fillers, low conc.of non-reinf. 9.5 1.0 None None 17.9 1.0 fillers, B component Ex. 13Medium conc. of reinf. fillers, medium conc. of 9.1 1.1 Medium Medium18.5 1.1 non-reinf. fillers, A component Ex. 14 Medium conc. of reinf.fillers, medium conc. of 7.6 1.2 Medium Medium 12.0 1.2 non-reinf.fillers, B component Ex. 16 Low conc. of reinf. fillers, high conc. ofnon-reinf. 9.0 1.0 Severe Severe 11.0 1.1 fillers, A component Ex. 17Low conc. of reinf. fillers, high conc. of non-reinf. 9.9 1.3 SevereSevere 15.7 1.5 fillers, B component Ex. 18 Low conc. of reinf. fillers,high conc. of non-reinf. 8.5 1.1 Severe Severe 8.6 1.1 fillers, BET: 200m²/g, A component Ex. 20 Low conc. of reinf. fillers, high conc. ofnon-reinf. 9.4 1.2 Severe Severe 13.4 1.7 fillers, BET: 200 m²/g, Bcomponent Ex. 22 Only reinforcing fillers, BET: 200 m²/g, A 9.2 1.0 NoneNone 9.2 1.0 component Ex. 23 Only reinforcing fillers, BET: 200 m²/g, B9.1 1.0 None None 9.1 1.1 component Ex. 25 Inventive impressionmaterial, A component, 6.7 1.1 None None 8.1 1.4 7.5 Pas Ex. 26Inventive impression material, B component, 7.3 1.0 None None 7.9 1.17.5 Pas Ex. 28 As example 25, but undried filler 6.7 1.1 None None 8.11.4 Ex. 29 As example 26, but undried filler 7.3 1.0 None None 7.9 1.1Ex. 31 Inventive impression material, A component, 40 Pas 36.8 1.2 NoneNone 38.2 1.1 Ex. 32 Inventive impression material, B component, 40 Pas25.5 1.1 None None 28.4 1.2 Ex. 34 Commerical low-viscous correctionimpression 10.9 9.0 Moderate Moderate 23.0 5.7 material, A Ex. 35Commercial low-viscous correction impression 16.0 49.0 Moderate Moderate20.0 64.0 material, B ¹⁾The viscosity is measured using a RS 150viscosimeter of the Haake company at 23° C. Oscillation frequency: 1 Hz;cone plate system; 35 mm; 4° cone; shear stress: 50 Pa; for evaluation,the viscosity value is read off after a measuring time of 80 s.

TABLE 2 technical data of the examples (single components)¹⁾ Examples 3to 24, 30, and 36 are comparative examples Examples 27 and 33 areexamples according to the invention Example 3 Example 6 Example 9Example 12 Example 15 Example 18 Description Without fillers Onlyreinforcing Only non-rein- High concentration of Medium concentrationLow concentration of rein- fillers forcing fillers reinforcing, lowconc. of reinforcing and non- forcing (BET: 140 m²/g), (BET: 140 ofnon-reinforcing reinforcing fillers high conc. of non-reinforc- m²/g)fillers ing fillers Mixed viscosity⁹⁾ 5.0 Pas 9.0 Pas 10.0 Pas 9.2 Pas9.5 Pas 8.5 Pas Thixotropic index of 1.0 1.0 1.1 1.1 1.0 1.1 themixture⁸⁾ Processing time¹⁰⁾  60 s  30 s  60 s  60 s  40 s  60 s End ofsetting¹¹⁾ 240 s 270 s 230 s 240 s 270 s 230 s Recovery of shape 99.80%99.60% 99.40% 99.40% 99.40% 99.70% (ISO 4823) Plasticity and 11.00%5.50% 1.90% 6.40% 3.30% 2.70% pressure (ISO 4823) Shore A hardness¹²⁾ 1834 73 31 54 57 Tear resistance¹³⁾ ⁷⁾ 103 N/cm² 308 N/cm² 135 N/cm² 203N/cm² 272 N/cm² Tear propagation 0.1 N/mm 0.41 N/mm 0.77 N/mm 2.59 N/mm0.64 N/mm 0.73 N/mm strength¹⁴⁾ Impression result Insufficient PoorInsufficient Poor Poor Poor employing the novel too brittle³⁾ toobrittle³⁾ too hard too brittle³⁾ sedimentates⁴⁾ sedimentates⁴⁾impression spoon¹⁵⁾ sedimentates⁴⁾ End of setting, 220 s 260 s 270 s 240s 270 s 185 s 1 week, 60° C. Mixed viscosity, 4.6 Pas 6.3 Pas 10.2 Pas10.7 Pas 13.9 Pas 12.4 Pas 1 week, 60° C. Thixotropic index, 1.0 1.0 1.11.0 1.4 1.1 3 weeks, 60° C. Example 21 Example 24 Example 27 Example 30Example 33 Example 36 Description Low concentra- Only reinforcingAccording to Comprising the inven- According to the Commercial, lowviscous tion or reinfor- fillers (BET: the invention, tive filler, butundried invention, 40 Pas, correction material²⁾ cing (BET: 200 m²/g)7.5 Pas, BET: BDT: 35 m²/g 200 m²/g), high 35 m²/g conc. of non-reinforcing fillers Mixed viscosity⁹⁾ 6.4 Pas 7.1 Pas 7.3 Pas 7.3 Pas39.8 Pas 38.9 Pas Thixotropic index 1.1 1.1 1.1 1.1 1.1 1.7 of themixture⁸⁾ Processing time¹⁰⁾  60 s  60 s  60 s  60 s  60 s  60 s End ofsetting¹¹⁾ 230 s 240 s 215 s 215 s 180 s 150 s Recovery of shape 99.60%99.70% 99.80% 99.90% 99.90% 99.80% (ISO 4823) Plasticity and 3.40% 6.40%6.40% 6.40% 6.30% 4.60% pressure (ISO 4823) Shore A hardness¹²⁾ 51 31 4141 35 46 Tear resistance¹³⁾ 170 N/cm² 40 N/cm² 225 N/cm² 225 N/cm² 174N/cm² 200 N/cm² Tear propagation 0.59 N/mm 0.32 N/mm 0.59 N/mm 0.59 N/mm2.09 N/mm 2.09 N/mm strength¹⁴⁾ Impression result Poor Poor ExcellentExcellent Good Poor employing the novel sedimentated⁴⁾ too brittle³⁾instable¹⁵⁾ too thixotropic⁹⁾ impression spoon¹⁵⁾ End of setting, 175 s280 s 215 s 600 s 180 s 150 s 1 week, 60° C. Mixed viscosity, 7.6 Pas7.4 Pas 7.3 Pas 6) 39.8 Pas 60.2 Pas 1 wee, 60° C. Thixotropic index,1.0 1.0 1.1 6) 1.1 2.6 3 weeks, 60° C. ¹⁾The technical data preventingor limiting the usability of the respective comparative example for thenovel impression spoon are marked in bold and italics ²⁾Pansil ContactPlus, batch no. 1999, Kettenbach GmbH & Co KG ³⁾The cured impressioncracks during the removal from the patient's mouth or during the removalfrom the impression spoon or breaks through ⁴⁾After storage, theproperties of the mixed and cured impression material are impaired dueto the sedimentation of the single components ⁵⁾When flowing around theteeth, the thixotropically adjusted material causes flow trails in theareas averted from the flow direction which falsify the impressionresult ⁶⁾The mixed viscosity and the thixotropic index cannot bemeasured unambiguously due to the excessive delay during crosslinking⁷⁾The material already cracks during the mounting in the testingapparatus; a meaningful measurement is not possible. ⁸⁾The thixotropicindex is the quotient of the viscosity after a measuring time of 25 sand the minimum of viscosity (mixed viscosity) ⁹⁾The mixed viscosity ismeasured in a RS 150 viscosimeter of the Haake company at 35° C.Oscillation frequency: 1 Hz; plate-plate measuring system; 20 mmcross-serrated; plate distance: 0.25 mm; constant shear stress: 50 Pafor 90 s; subsequently: shear stress ramp; 120 Pa/min; for evaluation,the viscosity value at the minimum of the viscosity curve is used as themixed viscosity for the table ¹⁰⁾The given processing time is the timeafter the beginning of mixing in which the mixed viscosity at 35° C.changes only insignificantly. ¹¹⁾The end of setting is measured in ashearing disk oscillometer of the Brabender Company, Cycloviskograph E;oscillation frequency: 4 Hz, gap width: 0.5 mm; cross-serrated plates¹²⁾The Shore A hardness is measured in a Shore A Durometer of the ZwickCompany, model 3100, according to DIN 53504 ¹³⁾The tear resistance ismeasured in a Z010 niversal test apparatus of the Zwick companyaccording to DIN 53515 ¹⁴⁾The tear propagation resistance is measured ina Z010 niversal test apparatus of the Zwick company according to DIN53515 ¹⁵⁾The impression is performed according to WO-A-97/32536 andWO-A-98/52491 ¹⁶⁾Immediately after the preparation, the impressionmaterial has the same positive features as example 27. However, sincethe employed filler contains water, a decomposition of the platinumcatalyst and the SiH crosslinking agent occurs in the storage time whichresults in a delayed setting. A use in the novel impression spoon is notoptimal.

TABLE 3 Viscosities of the mixture of low-viscous impression materialsMixed Thixotropic Mixing Processing End of Product Manufacturer TypeBatch viscosity²⁾ index³⁾ time³⁾ time⁴⁾ curing⁵⁾ Lastic Xtrasuperfine/Lastic Xtra Kettenbach C silicone 0299/0499 27.3 Pas ¹⁾ 45 s70 s 430 s Fl{overscore (u)}ssighärter Xantopren VL plus/Aktivatoruniversal Heraeus-Kutzer C silicone 090079/100241 1100.4 Pas ¹⁾ 45 s  0s 220 s Panasil Contact Plus Kettenbach A silicone 1999 38.9 Pas 1.7 5 s60 s 1506 Provil light CD Heraeus-Kutzer A silicone 120098 154.6 Pas 1.05 s 35 s 160 s Permadyne Tube dünnflieβend Espe Polyether RW0057004 66.3Pas 1.0 45 s 75 s 440 s Permadyne Garant 2:1 Espe Polyether 29817 31.4Pas 1.0 5 s 35 s 427 s Dimension Garant L Espe A silicone 22 50.9 Pas1.1 5 s 40 s 280 s Dimension Grarant L Quick Espe A silicone 6 449.2 Pas¹⁾ 5 s 35 s 140 s Aquasil LV Dentaply A silicone 960702 79.3 Pas ¹⁾ 5 s25 s 277 s President light body Coltene A silicone GF092/GE003 59.8 Pas¹⁾ 5 s 25 s 180 s ¹⁾The thixotropic index cannot be determined since thethixotropy is superimposed by the beginning setting ²⁾The mixedviscosity is measured in a RS 150 viscosimeter of the Haake Company at35° C.; oscillation frequency: 1 Hz; plate-plate measuring system; 20 mmcross-serrated; plate distance: 0.25 mm; constant shear stress: 50 Pafor 90 s; subsequently: shear stress ramp; 120 Pa/min; for evaluation,the viscosity value at the minimum of the viscosity curve is used as themixed viscosity for the table ³⁾The thixotropic index is the quotient ofthe viscosity after a measuring time of 25 s and the minimum ofviscosity (mixed viscosity) ⁴⁾the given processing time is the timeafter the beginning of mixing in which the mixed viscosity at 35° C.changes only insignificantly. ⁵⁾The end of setting is measured in ashearing disk oscillometer of the Brabender Company, Cycloviskograph E;oscillation frequency: 4 Hz, gap width: 0.5 mm ⁶⁾Lastic Xtra superfine,Xantopren VL plus, and Permadyne Tube dünnflieβend: theses materials aremanually mixed on a mixing block by means of a mixing spatula

What is claimed is:
 1. An impression material for the use with animpression spoon in a patient, the impression material comprising acurable component and at least one first filler, characterized in thatsaid at least one first filler has a BET surface of 20 to 50 m²/g and ispresent in amount of 10 to 50% by weight, and the impression materialhas a thixotropic index ≦1.1 and a viscosity of 1 to 40 Pas.
 2. Theimpression material according to claim 1, characterized in that said atleast one first filler has a BET surface of 30 to 40 m²/g and theimpression material has a viscosity of 1 to 10 Pas.
 3. The impressionmaterial according to claim 1, characterized in that, due to the use ofthe first filler, no polymer separation and filler sedimentationtendencies and no poststiffening occur during storage life of at least18 months.
 4. The impression material according to claim 1,characterized in that, due to the use of the first filler, tearresistance in the cured state measured according to DIN 53504 is between150 and 250 N/cm².
 5. The impression material according to claim 1,characterized in that the curable component comprises hydrocolloids,alginates, polyethers, plastics, plasters, condensation-crosslinkingsilicones, addition-crosslinking silicones, or addition-crosslinkingsilicone polyethers.
 6. The impression material according to claim 2,characterized in that said impression material containsaddition-crosslinking silicones and addition-crosslinking siliconepolyethers.
 7. The impression material according to claim 1,characterized in that said impression material is processable in 20 to120 s and a curing at the temperature of the mouth (35° C.) occurswithin 240 s.
 8. The impression material according to claim 1, whereinsaid first filler is a wet-precipitated silicic acid or a naturallyoccurring silicic acid having a water content of 2 to 8% by weight. 9.The impression material according to claim 1, wherein said first fillerhas a density of 2.0 to 2.2 g/cm³, a dibutyl phthalate adsorptionaccording to DIN 53601 between 140 and 180 g/100 g, oil adsorptionaccording to DIN ISO 7875 between 35 and 60 g/100 g, and/or a meanparticle size between 0.5 and 20 μm.
 10. The impression materialaccording to claim 1, wherein said impression material further comprisesat least one second filler having a density between 2.0 and 2.2 g/cm³, aBET surface between 110 and 170 m²/g, and/or a primary particle sizebetween 5 and 30 nm.
 11. The impression material according to claim 1,wherein said impression material further comprises a second fillerhaving a density between 2.0 and 2.2 g/cm³, a BET between 130 and 150m²/g, and/or a primary particle size between 5 and 30 nm.
 12. Theimpression material according to claim 1, wherein said first fillercomprises silicon dioxide and metal oxides.
 13. The impression materialaccording to claim 1, wherein said first filler comprises silicondioxide and a metal oxide, wherein the metal oxide is aluminum oxide,calcium oxide, sodium oxide, potassium oxide, iron oxide, or titaniumdioxide.
 14. The impression material according to claim 1, wherein saidfirst filler comprises silicon dioxide in amounts of from 80 to 100% andmetal oxides in amounts of from 0 to 20%.
 15. The impression materialaccording to claim 10, wherein said at least one first and/or said atleast one second filler is (are) hydrophobized.
 16. The impressionmaterial according to claim 1, further comprising a second fillerexisting highly dispersed in the form of hydrophobized silicic acid andthe second filler has been prepared by a flame hydrolysis of silicontetrachloride.
 17. The impression material according to claim 1,comprising addition-crosslinking silicones containing components: a)unsaturated polysiloxanes, alkenylpolysiloxanes, b)organohydrogenpolysiloxanes, and c) catalysts.
 18. The impressionmaterial according to claim 1, comprising addition-crosslinkingsilicones containing components: a) α,ω-unsaturated polysiloxanes,α,ω-alkenylpolysiloxanes, b) organohydrogenpolysiloxanes, and c)catalysts.
 19. The impression material according to claim 1,characterized in that component a) contains α,ω-dialkyl, diaryl,arylalkyl, α,ω-alkenyl, or vinylpolysiloxanes, substituted dialkyl,diaryl, or arylalkyl polysiloxanes or polyethers, orα,ω-vinyl-terminated polydimethylsiloxanes in an amount of 40 to 80% byweight.
 20. The impression material according to claim 1, characterizedin that component a) contains α,ω-dialkyl, diaryl, arylalkyl,α,ω-alkenyl, or vinylpolysiloxanes, substituted dialkyl, diaryl, orarylalkyl polysiloxanes or polyethers, or α,ω-vinyl-terminatedpolydimethylsiloxanes in an amount of 50 to 70% by weight.
 21. Theimpression material according to claim 1, characterized in thatcomponent b) contains alkyl or arylorganohydrogenpolysiloxanes.
 22. Theimpression material according to claim 17, characterized in thatcomponent b) contains polyhydrogenpolydimethylsiloxanes having at least2 SiH groups or an SiH content of from 0.1 to 15 mmol/g in an amount of2 to 40% by weight.
 23. The impression material according to claim 17,characterized in that component b) containspolyhydrogenpolydimetbylsiloxanes having at least 2 SiH groups or an SiHcontent of from 0.1 to 15 mmol/g in an amount of 10 to 30% by weight.24. The impression material according to claim 17, characterized in thatcomponent c) contains catalysts of transition metals of the 8^(th) sidegroup of the periodic system in a percentage range of 0.0001 to 0.1% byweight based on the pure metal.
 25. The impression material according toclaim 17, characterized in component c) contains catalysts, salts, orforms of transition metals of the 8^(th) side group of the periodicsystem existing as complexes or colloids in a percentage range of 0.0001to 0.1% by weight based on the pure metal.
 26. The impression materialaccording to claim 17, characterized in that component c) containshydrosilylation catalysts, salts, or forms of platinum, palladium, orrhodium existing as complexes or colloids in a percentage range of0.0001 to 0.1% by weight based on the pure metal.
 27. The impressionmaterial according to claim 17, characterized in that component c)contains platinum complexes prepared from hexachloroplatinic acid orfrom platinum salts (Karstedt catalysts) in a percentage range of 0.0001to 0.1% by weight based on the pure metal.
 28. The impression materialaccording to claim 27, characterized in that the percentage range is0.0005 to 0.1% by weight based on the pure metal.
 29. The impressionmaterial according to claim 1, wherein said first filler is present inan amount range of 20 to 30% by weight.
 30. The impression materialaccording to claim 1, comprising polysiloxanes having methacrylategroups and an initiator system activatable by light.
 31. The impressionmaterial according to claim 1, comprising polysiloxanes havingmethacrylate groups and an initiator system activatable by UV light. 32.The impression material according to claim 17, characterized in thatingredients a) and c) exist in a spatially separated manner.
 33. Theimpression material according to claim 1, characterized in that saidfirst filler is inorganic and the impression material further comprisesa second filter, the second filler being an inorganic, reinforcingfiller hang a BET surface greater than the BET surface of the firstfiller.
 34. The impression material according to claim 33, wherein thesecond filler has a BET surface of from 50 to 700 m²/g.
 35. Theimpression material according to claim 33, wherein the second filler hasa BET surface of from 110 to 170 m²/g.
 36. The impression materialaccording to claim 33, wherein said first filler is a wet-precipitatedsilicic acid or a naturally occurring silicic acid having a watercontent of 2 to 8% by weight.
 37. The impression material according toclaim 33, wherein said first filler has a density of 2.0 to 2.2 g/cm³, adibutyl phthalate adsorption according to DIN 53601 between 140 and 180g/100 g, an oil adsorption according to DIN ISO 7875 between 35 and 60g/100 g and/or a mean particle size between 0.5 and 20 μm.
 38. Theimpression material according to clam 33, wherein the second filler ishydrophobized.